1. Technical Field
The present invention relates to a hard disk drive controller, an image forming apparatus, and a storage medium on which a computer program has been recorded.
2. Related Art
A technique is proposed for raising the reliability of a hard disk drive (referred to as HDD below) by reducing the duration that a magnetic head resides above a magnetic disk, or by reducing the number of load/unload cycles of a magnetic disk. This is achieved by providing non-volatile memory to the HDD, temporarily accumulating write-data on the non-volatile member, and writing the accumulated data onto the magnetic disk when a read command has been issued and the head is in the loaded state.
3.5 inch HDDs, however, have a high speed of data recording/reproduction and are often installed in applications that require a high operation speed, such as in color printers. 3.5 inch HDDs are also often used in applications which have long periods of continuous operation. There is therefore an expectation that there will be about one occasion per day when there is switching between power supply on/power supply off, and the head is retracted from the disk. Control is therefore preferably carried out so as to reduce switching between the power supply on/power supply off and between motor rotation on/motor rotation off, and to reduce retractions of the head. 3.5 inch HDDs are also often applied in applications to which no energy consumption reducing mechanism has been included and which have a large energy consumption.
2.5 inch HDDs, in contrast, are often installed in systems which prioritize low energy consumption and energy saving. Systems which prioritize energy saving, for example, are systems that reduce energy consumption by frequently ceasing power supply to the HDD when the HDD is not being used. In addition, the HDD itself also enters an energy saving mode when there has been no access to the HDD for a given duration, and reduces energy consumption by, for example, retracting the head and ceasing power supply to a portion of the internal circuit of the HDD, supplying power only to the remaining necessary portion thereof. Since there are frequent cessations of power supply to the 2.5 inch HDDs in this manner, the expected power supply duration in a day is of the order of a few hours, and a state of continuous power supply should be avoided. The rotational duration of the motor is also limited, and continuous rotation of the motor should also be avoided.
However, even within the same type of systems, 2.5 inch HDDs installation is appropriate where, for example, energy saving is prioritized, but 3.5 inch HDDs installation is appropriate when, for example, high volumes of copying are to be performed and printing is to be carried out for long durations. Therefore, the most appropriate HDD differs may depend on the actual application, even within the same type of system.
The speed of data recording and reproduction of 2.5 inch HDDs has recently approached that of old 3.5 inch HDDs, and there are occasions where a 2.5 inch HDD is installed for an application that conventionally was installed with a 3.5 inch HDD. 3.5 inch HDDs are also cheaper than 2.5 inch HDDs due to their differing volumes of production.
Therefore HDDs may be installed with different external dimensions according to the application and the purpose, even within the same system.